[R] thicker axis in levelplot

[Jenny Barnes]

Dear R-help community,

I need to find out how to make the black axis line around my plot thicker in 
levelplot, I cannot find the correct command in ?levelplot or ?par - or if it is 
there I cannot get it to work - any help would be more that appreciated!

Here's an example script - I would want the code for making the axis bordering 
the plot thicker:

x<- seq(pi/4, 5*pi,length=100)
y<- seq(pi/4, 5*pi,length=100)
r<- as.vector(sqrt(outer(x^2,y^2,"+")))
grid<- expand.grid(x=x,y=y)
grid$z <- cos(r^2) * exp(-r/(pi^3))

levelplot(z~x*y, grid, cuts=50, scales=list(log="e"), xlab="",
	   ylab="", main="Weird Function", sub="with log scales",
	   colorkey=FALSE, region=TRUE)


Also, If anybody knows how to make the lines around the colorkey (legend) 
thicker too I'd like to do that as well! (I realise that the above script does 
not include a colorkey component but my actual work does).

Many thanks,

Jenny Barnes